diff --git a/src/main/kotlin/dev/usbharu/hideout/service/ap/resource/InMemoryCacheManager.kt b/src/main/kotlin/dev/usbharu/hideout/service/ap/resource/InMemoryCacheManager.kt
index be0abde5..12bdc70a 100644
--- a/src/main/kotlin/dev/usbharu/hideout/service/ap/resource/InMemoryCacheManager.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/service/ap/resource/InMemoryCacheManager.kt
@@ -1,27 +1,40 @@
 package dev.usbharu.hideout.service.ap.resource
 
 import dev.usbharu.hideout.domain.model.ap.Object
+import dev.usbharu.hideout.util.LruCache
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import org.springframework.stereotype.Service
+import java.time.Instant
 
 @Service
 class InMemoryCacheManager : CacheManager {
-    private val cacheKey = mutableSetOf<String>()
+    private val cacheKey = LruCache<String, Long>(15)
     private val valueStore = mutableMapOf<String, Object>()
     private val keyMutex = Mutex()
 
     override suspend fun putCache(key: String, block: suspend () -> Object) {
-        val hasCache: Boolean
+        val needRunBlock: Boolean
         keyMutex.withLock {
-            hasCache = cacheKey.contains(key)
-            cacheKey.add(key)
+            cacheKey.filter { Instant.ofEpochMilli(it.value).plusSeconds(300) <= Instant.now() }
+
+            val cached = cacheKey.get(key)
+            if (cached == null) {
+                needRunBlock = true
+                cacheKey[key] = Instant.now().toEpochMilli()
+
+                valueStore.remove(key)
+            } else {
+                needRunBlock = false
+            }
         }
-        if (hasCache.not()) {
+        if (needRunBlock) {
             val processed = block()
 
-            valueStore[key] = processed
+            if (cacheKey.containsKey(key)) {
+                valueStore[key] = processed
+            }
 
         }
     }
@@ -29,6 +42,9 @@ class InMemoryCacheManager : CacheManager {
     override suspend fun getOrWait(key: String): Object {
 
         while (valueStore.contains(key).not()) {
+            if (cacheKey.containsKey(key).not()) {
+                throw IllegalStateException("Invalid cache key.")
+            }
             delay(1)
         }
         return valueStore.getValue(key)
diff --git a/src/main/kotlin/dev/usbharu/hideout/util/LruCache.kt b/src/main/kotlin/dev/usbharu/hideout/util/LruCache.kt
new file mode 100644
index 00000000..ed0c3661
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/util/LruCache.kt
@@ -0,0 +1,14 @@
+package dev.usbharu.hideout.util
+
+import java.io.Serial
+
+class LruCache<K, V>(private val maxSize: Int) : LinkedHashMap<K, V>(15, 0.75f, true) {
+
+    override fun removeEldestEntry(eldest: MutableMap.MutableEntry<K, V>?): Boolean = size > maxSize
+
+    companion object {
+        @Serial
+        private const val serialVersionUID: Long = -6446947260925053191L
+    }
+
+}
diff --git a/src/test/kotlin/dev/usbharu/hideout/service/ap/resource/APResourceResolveServiceImplTest.kt b/src/test/kotlin/dev/usbharu/hideout/service/ap/resource/APResourceResolveServiceImplTest.kt
index 16b171ff..068cfe5f 100644
--- a/src/test/kotlin/dev/usbharu/hideout/service/ap/resource/APResourceResolveServiceImplTest.kt
+++ b/src/test/kotlin/dev/usbharu/hideout/service/ap/resource/APResourceResolveServiceImplTest.kt
@@ -1,5 +1,6 @@
 package dev.usbharu.hideout.service.ap.resource
 
+import dev.usbharu.hideout.domain.model.ap.Object
 import dev.usbharu.hideout.domain.model.hideout.entity.User
 import dev.usbharu.hideout.repository.UserRepository
 import io.ktor.client.*
@@ -52,7 +53,7 @@ class APResourceResolveServiceImplTest {
         val apResourceResolveService =
             APResourceResolveServiceImpl(httpClient, userRepository, InMemoryCacheManager(), objectMapper)
 
-        apResourceResolveService.resolve("https", 0)
+        apResourceResolveService.resolve<Object>("https", 0)
 
         assertEquals(1, count)
     }
@@ -87,10 +88,10 @@ class APResourceResolveServiceImplTest {
         val apResourceResolveService =
             APResourceResolveServiceImpl(httpClient, userRepository, InMemoryCacheManager(), objectMapper)
 
-        apResourceResolveService.resolve("https", 0)
-        apResourceResolveService.resolve("https", 0)
-        apResourceResolveService.resolve("https", 0)
-        apResourceResolveService.resolve("https", 0)
+        apResourceResolveService.resolve<Object>("https", 0)
+        apResourceResolveService.resolve<Object>("https", 0)
+        apResourceResolveService.resolve<Object>("https", 0)
+        apResourceResolveService.resolve<Object>("https", 0)
 
         assertEquals(1, count)
     }
@@ -127,17 +128,17 @@ class APResourceResolveServiceImplTest {
 
         repeat(10) {
             awaitAll(
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
-                async { apResourceResolveService.resolve("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
+                async { apResourceResolveService.resolve<Object>("https", 0) },
             )
         }
 
@@ -174,9 +175,9 @@ class APResourceResolveServiceImplTest {
         val apResourceResolveService =
             APResourceResolveServiceImpl(httpClient, userRepository, InMemoryCacheManager(), objectMapper)
 
-        apResourceResolveService.resolve("abcd", 0)
-        apResourceResolveService.resolve("1234", 0)
-        apResourceResolveService.resolve("aaaa", 0)
+        apResourceResolveService.resolve<Object>("abcd", 0)
+        apResourceResolveService.resolve<Object>("1234", 0)
+        apResourceResolveService.resolve<Object>("aaaa", 0)
 
         assertEquals(3, count)
     }